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arXiv · 0909.0186

Antiproton-nucleus electromagnetic annihilation as a way to access the proton timelike form factors

H. Fonvieille·V. Karmanov
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Abstract

Contrary to the reaction pbar + p --> e+ e- with a high momentum incident antiproton on a free target proton at rest, in which the invariant mass M of the (e+ e-) pair is necessarily much larger than the (pbar p) mass, in the reaction pbar + d --> n e+ e- the value of M can take values near or below the (pbar p) mass. In the antiproton-deuteron electromagnetic annihilation, this allows to access the proton electromagnetic form factors in the time-like region of q^2 near the (pbar p) threshold. We estimate the cross section dsigma(pbar +d --> e+ e- n)/dM for an antiproton beam momentum of 1.5 GeV/c. We find that near the (pbar p) threshold this cross section is about 1 pb/MeV. The case of heavy nuclei target is also discussed. Elements of experimental feasibility are presented for the process pbar + d --> n e+ e- in the context of the Panda project.

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H. Fonvieille, V. Karmanov. 2009-09-01. Antiproton-nucleus electromagnetic annihilation as a way to access the proton timelike form factors. https://doi.org/10.1140/epja%2Fi2009-10884-4

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